The main bone of contention was the use of dissonance (jarring pitches, and especially ones that came out of the blue) as a way of grabbing the listener’s attention and highlighting the meaning of a text.
The author had just attended a performance of madrigals by an unspecified composer, that broke all kinds of rules that had been observed for hundreds of years. He considered it absolutely preposterous to have been subjected to such “shocking sounds” that he considered “harsh and little pleasing to the ear.”
His letter got a lot of attention, but a mixed reaction. There were some who shared his opinion, especially if it had to do with religious music, where the main goal was to awe the listener as a way of glorifying God, and inspiring worship. But many others felt equally strongly, that life itself is messy and convoluted and music should be able to communicate all kinds of human experiences and emotions, a hallmark of Baroque Music.
The debate was fast and furious, and it took a while for the composer of the original madrigals to gather enough support and courage to step forward to take ownership and responsibility. But in 1607, Claudio Monteverdi did exactly that, saying that his compositional style was intentional, and created to “satisfy both the mind, and the senses.” Monteverdi described the old style as one that focused on a perfection of harmony, whereas the new style centred on melody, and “makes words the mistress of harmony.”
Though Monteverdi’s use of dissonance might seem somewhat tame to 21st century ears, his was a novel approach at the time. It established a clear perception of “melody” vs “accompaniment” that in Monteverdi’s words “built upon the foundation of truth.” This approach has opened the door for an ever-richer harmonic language and palette, that has only continued to expand in music of all types over the last 400 years.